1. Field of the Invention
This invention is directed to a gantry with an attached crane mounted on a railroad freightcar and more particularly to a gantry and crane designed for handling large and bulky materials such as railroad tie bundles, rail culverts, poles, switches, etc. and loading or unloading them from the freightcar on which it is mounted or surrounding freightcars, and an apparatus and method for safely retaining the gantry on the freightcar.
2. Description of the Related Art
In modern railroad operations, it is common for railroad tracks, including rails, ties and ballast, to be replaced in large sections. This is often accomplished by special high capacity track renewal trains which include a number of railroad freightcars, each of which can accommodate large numbers of new ties, rails, culverts, etc. At least some of the freightcars in the train are equipped with a special pair of rails permanently affixed to the top thereof, and extending along each side of the freightcar. The special renewal train has at least one traveling gantry which can operate along the freightcar rails to transport material to or from the associated or surrounding freightcars. The gantry or gantries can be moved from car to car within the train as needed.
Such freightcar mounted gantries have supported both vertical hoists for lifting and transporting material along the cars, and power-driven cranes with extendable booms designed for considerable reach away from the cars.
A potentially dangerous problem associated with such prior art gantries, and particularly those supporting cranes, has been the tendency for tipping from side-to-side, given the necessarily high center of gravity of the crane and the large moment arm presented by the boom. In addition, operators of such gantries have had a tendency to drive them completely off of the rails on the freightcar, resulting in overturned and damaged gantries, and consequent danger to the operator and surrounding personnel.
It is clear, then, that a real need exists for a freightcar mounted gantry and crane which is designed to prevent these problems. Such a gantry should resist tipping and, in the event that either end is driven past the freightcar-mounted rails, the gantry should be prevented from overturning or otherwise falling off of the freightcar. For reasons of economy, such a gantry should be capable of accepting existing commercially available cranes.